Process for spinning high tenacity fibres

ABSTRACT

Poly(ethylene-1:2-diphenoxyethane-4:4&#39;&#39;-dicarboxylate) extruded to give spun yarn birefringence above 60 X 10 3 and not above value by equation Delta 18 X 10 6 W + 50 X 10 3 where Delta is spun yarn birefringence and W is wind up speed, followed by orientation by extension.

United States Patent [191 Harris et al.

[ 51 Aug. 27, 1974 PROCESS FOR SPINNING HIGH TENACITY FIBRES [75] Inventors: Eric Frank Harris, Greenisland,

Northern Ireland; John Francis Lloyd Roberts, Harrogate, England [73] Assignee: Imperial Chemical Industries Limited, London, England [22] Filed: Mar. 30, I973 [21] Appl. No.: 346,490

[30] Foreign Application Priority Data Apr. 6, 1972 Great Britain 15848/72 [52] US. Cl. 214/210 F, 280/47 C, 264/290 T [51] Int. Cl. D0lf 3/10 [58] Field of Search 264/168, 290 T, 176 F,

[56] References Cited UNITED STATES PATENTS 3,361,859 1/1968 Cenzafo 264/210 F Primary Examiner]ay I-I. Woo Attorney, Agent, or Firm-Roderick B. Macleod; Stephen D. Murphy; Thomas J. Morgan ABSTRACT Poly(ethylenel :2-diphenoxyethane-4:4 dicarboxylate) extruded to give spun yarn birefringence above 60 X 10 and not above value by equation A =18 X 10 W 50 X 10* where A is spun yarn birefringence and W is wind up speed, followed by orientation by extension.

5 Claims, No Drawings PROCESS FOR SPINNING HIGH TENACITY FIBRES The present invention relates to the manufacture of yarns by the melt-spinning of poly(ethylene-lz2- diphenoxyethane-4:4-dicarboxylate).

According to the present invention we provide a process for the manufacture of a yarn of poly(ethylene- 1:2-diphenoxyethane-4z4 '-dicarboxylate) or its copolyester wherein poly(ethylene-1:2-diphenoxyethane- 4:4'-dicarboxylate) or a copolyester of it is extruded under conditions to give a spun yarn of birefringence in excess of 60 X but not in excess of the value given by the equation where A is the spun yarn birefringence and W is the wind up speed, followed by orientation by extension.

Preferably the spun birefringence should be in excess of l 10 X 10 and should not exceed the value given by the equation A'= 16.2 X10 W+ 50 X 10 By a copolyester of poly( ethylene-l :2- diphenoxyethane-4-4'-dicarboxylate) we mean a copolyester of which at least 90 percent of the structural units are of the formula:

Such copolyesters may contain in the chain minor amounts of other structural units derived from glycols other than ethylene glycol and/or from dicarboxylic acids other than bis-l:2-(paracarboxyphenoxy)ethane and/or from a hydroxycarboxylic acid.

The poly( ethylene-l :2-diphenoxyethane-4:4- dicarboxylate) or its copolyester for use in accordance with our invention may be manufactured by known methods and may contain one or more additives, for example delustrants, pigments, optical brighteners or stabilizers.

The yarns of our invention are of particular value when the poly(ethylene-l:2-diphenoxyethane-4:4'- dicarboxylate) or copolyester comprising them is of relative viscosity, as measured in orthochlorophenol at a concentration of l g. per 100 ml. of solvent and at a temperature of 25 C., greater than 2.0.

We have found it preferable to operate the process of our invention so that the spun yarn produced is amorphous, while still having a high 'spun birefringence. The preference for amorphous yarn arises from the fact that crystallinity in the spun yarn results in lower extensibility in the drawn product. By arnorphous we mean that examination by X-ray diffraction showed no crystallinity.

The crystallinity of the spun yarn may be controlled by appropriate choice of relative viscosity of the poly(- ethylenel :2-diphenoxyethane-4:4-dicarboxylate) and of the parameters of the melt-spinning. Thus crystallinity is favoured by increase in stress which is increased by increase in relative viscosity. increase in spinneret hole size for a given spun denier, reduction in the temperature of the poly(ethylene-l:Z-diphenoxyethane- 4:4-dicarboxylate) at extrusion, increase in rate of cooling in the molten region of the threadline, and increase in draw-down during spinning.

The ease of drawdown in forming the spun yarn will be, inversely related to the viscosity of the extrudate, and the desirable spinning temperature will increase with yarn relative viscosity. We have found that for relative viscosities from 2.0 to 2.3 the desirable spinning temperature is in the range 295 to 335 C. In the case of the higher relative viscosities, it may be preferable to reduce the rate of filament cooling, for example by the use of a heated threadline shroud as described in U.K. Pat. No. 1,052,067, rather than to use impracticably high extrusion temperatures.

Spun yarns of poly(ethylene-l:2-diphenoxyethane- 4:4'-dicarboxylate) have the characteristic that when heated under low or zero tension they either shrink or increase in length spontaneously dependent on the initial spun yarn birefringence and on the temperature of heating. We have found that if we prefer to draw yarns of high birefringence, then there is less danger of undesirable spontaneous expansion prior to drawing if the value of the birefringence is at or above X 10*. Below this value the spontaneous expansion of the product renders it more difficult to maintain control of spun yarn tension as it passes over heated surfaces.

When the spun yarn expands spontaneously under zero tension as described above it also c'rystallises, the crystalline form (referred to as B crystallinity) has a monoclinic habit.

The crystallisation which occurs under stress, as during spinning, is of a different crystalline form having an orthorhombic habit (referred to as the a form). We have found that crystallisation under stress produces the a form; thus the crystallisation obtained under the spinning stress and during drawing using a pin only, for example as described in our U.K. Specification No. 1,047,978, is of the a form.

We have found, in our production of high relative viscosity high tenacity yarns that the modification of the drawing conditions to introduce some B crystallinity in the drawn yarn is beneficial, provided that the relative viscosity is above about 2.00.

When the cooling of the molten threadline is effected by contactwith the ambient air at normal room temperature, the relationship between spun yarn relative viscosity and extrusion temperature to yield optimum tensile properties in the yarn after drawing is given by the equation:

Extrusion temperature (89 X relative viscosity l28) C.

An advantage of the process of our invention is that by the use of it drawn yarns may be produced having a tenacity of greater than 9.5 g. per denier and an extension to break greater than 7 percent. Such yarns are of particular advantage for the manufacture of ropes, and cords. The cords are of particular use in the manufacture of tyres and V-belts, in which high modulus, good hydrolytic stability and low shrinkage are desirable. ln the case of the use of the yarns in ropes, the good light stability is a further advantage.

The orientation by extension, that is drawing, may be carried out by known methods. Heated feed rolls or heated snubber pins may be used; we have 'found the latter to be preferable.

ln order that our invention may the more clearly be understood, we give hereinafter examples of methods in which it may be carried out.

EXAMPLES 1 20 Poly( ethylene-l :2-diphenoxyethane-4z4 dicarboxylate) of relative viscosity (R.V. as measured in 1 percent by weight solution in orthochlorophenol at The lower relative viscosity yarn was shown by X-ray diffraction to be amorphous, whilst the higher relative viscosity yarn was shown to contain a significant amount of a-crystalline material.

25 C. as shown in Table l was melt-spun at a tempera- 5 s mglesglar yam ture as shown in Table 1. Other spinning conditions and i f Yg i 3 trawn yle e yams an the resultant spun birefringences are also given in amen q 0 l enor ex p l l The results are shown 1n Table 2. Table 1.

TABLE 1 No. of Spinneret Yurn Extrusion Shroud Wind Up Spun Yurn Example Filu hole diam. RV. Temp- Temp- Spccd Birc- Morpholmcnts inches craturc erature fpm. fringcnce ogy l 3 .035 2.04 280 None 500 XX 10" Amorphous 2 1000 21x10" d0. 3 1500 SSXIO" do. 4 2000 BBXIO" a-form 5 2500 98 l0"" do. 6 3500 115x10--" d0. 7 3 .020 2.00 301 305 1000 3.2 Amorphous 8 2000 1 1 10--'* d0. 9 3000 22 10-= do. 10 4000 53 10- do. 1 1 5000 1 12x10-" do. 12 6000 145 10"=* d0. 13 3 .009 2.07 292 None 4500 132x10-=* a-form l4 3 .009 2.05 303 None 4500 l l8 l0 Amorphous I5 48 .015 2.l3 312 None 4500 l33 l0 a-form I6 48 .015 2.07 31 I None 4500 125x10 Amorphous 17 3 .020 2.00 302 None 4000 139x10 a-form l8 3 .020 2.00 310 305 6000 145x 1 0- Amorphous 19 3 .035 1.96 290 None 5000 150 10- a-form 20 3 .009 L96 290 None 6000 l46 l 0 Amorphous RV signifies relative viscosity. fpm do. feet per minute.

Examples 1 10 are not according to the present inven- EXAMPLES 28 33 tion.

EXAMPLES 21 27 The following Examples show how in the absence of external heating effects, for example a threadline These Examples show that inferior drawn yarns are shroud, the spinning extrusion temperature varies obtained from a-crystalline spun yarn. w1th relative viscosity for the processes found to Yarns of 48 filaments having relative viseosities of yield the best drawn tensile properties at a given 2.07 and 2.13 respectively were extruded at about 310 relative viscosity level. C. and wound up to give spun yarns of birefringence The results ar h wn in Tabl 3 about 130 X 10".

TABLE 2 Example Yarn Spun Yarn Spun MaxDrawn RV Morphology Bire- Yarn Single Filament Tensile Properties fringence Tenacity Tenacity Extension 2% Modulus gm/denier gm/denier gm/denier/ [00% Extension 21 2.07 Amorphous 10- 8.9 9.8 8.2 198 22 8.4 9.2 8.5 197 23 8.0 8.8 8.9 194 24 7.1 7.8 11.0 170 25 2.13 Largely a- 133x10- 8.7 9.6 6.6 219 Crystalline 26 8.0 8.8 7.5 184 27 7.2 7.9 9.1 158 TABLE 3 Example RV in Spun Extrusion Maximum OC.P. Bire- Temp- Yarn Tensile Properties No. of

fringence crature Tenacity Extension 2% Modulus filaments C gm/den. A gm/denJ 100% Extension 28 1.53 5.5 10-= 265 54 3.8 174 5 2) L7) lUfiXlO' 290 0.] 4.6 220 5 .10 1.84 00x10" 290 9.5 (1.3 2m 5 31 2.02 x10 312 9.6 7.1 107 .1 32 2.08 95 10-= 312 9.: 7.7 183 :4 33 2.32 133x10 330 9.4 7.0 183 2-1 Example 28 is not according to the present invention.

From the data in Table 3 a trend line of optimum spinning temperature against yarn RV can be constructed. This relationship proves to be a good straight line curve which obeys the equation:

Optimum Spinning Temperature 89 X RV in 1% OC.P 128 C.

EXAMPLE 34 This example shows how the dimensional stability of amorphous spun yarn varies as a function of spun birefringence and temperature of heat treatment.

Yarns having spun birefringences varying from 4 X to 173 X 10' were spun. Hanks of these yarns were then suspended in a steam bath at 100 C for mins. and their change in length measured. Further samples of the yarns were then suspended in an air oven at 160 C for 15 minutes and their change in length again measured. The data for the variation of change in length with initial spun yarn birefringence at 100 and 160 C are given in table 7. From these data EXAMPLES 37 These examples demonstrate how both pin and plate temperatures affect the relative amounts of a and B-crystalline forms in the drawn product.

A 24 filament yarn was spun in a similar manner to that in case 11 to an RV of 2.08 at 312 C and collected at 3,500 fpm to give an amorphous spun yarn of birefringence 74 X 10 The yarn was shown to be capable of drawing at optimum conditions to give a product having a filament tenacity in excess of 10.0 gm/denier.

TABLE 5 Example Relative percentage of monoclinic B-form in the cgystalline regions of the drawn yarn Plate Temperatures 150C 170C 190C 210C 35 Pin Temperatures C 0 9 45 46 36 do. C 7 1 1 30 31 37 do. C 4 l 1 18 22 TABLE 4 EXAMPLES 38 43 These examples show that if the yarn is drawn in such a way that the drawn product is predominantly crystalline in the a-form the tensile properties are inferior, i.e., within a given context an increased proportion of B-form is favourable to tensile properties.

Filaments of relative viscosity 2.07 were extruded through a 48 hole spinneret at 312 C and wound up at speeds of 2,000 and 4,500 fpm to give spun yarns of birefringences 17 and 125 X 10 The yarns were shown to be amorphous as spun.

Variation of amorphous spun yarn dimensional stability at 100C. and C.

100C 160C Spun Change in length Spun Change in length Birefringence Birefringence 3.9 do. 1.6 3.9X103 +6 6.0 do. 1.6 6.0 do +4 7.6 do. l.4 7.6 do. +11 10.4 do. +0.5 11.8 do. +24 13.0 do. +4.2 13.0 d0. +14.2 13.9 do. +6.8 27.0 do. +29 24.0 do. +16.3 32.0 do. +26 27.0 do. +19.6 46.0 do. +23 32.0 do. +19.2 60.0 do. +18 38.0 do. +19.0 69.0 do. +15 46.0 do. +168 112.0 do. +5 61.0 do. +12.5 121.0 do. +4 68.0 do. +12.6 136.0 do. +3 81.0 do. +9.2 95.0 (10. +5.4 113.0 d0. +2.1 125.0 do. 40.7 135.0 do. +0.3 160.0 do. 1 .5

The minus sign indicates that shrinkage occurs. The plus sign indicates that elongation occurs.

The yarns were drawn over a heated pin and plate at a speed of 350 fpm, at the appropriate maximum draw ratio using the fixed optimum plate temperature while the pin temperature was varied. Data for these studies are given in table 6, the results show that above a pin temperature of 125 C a deterioration in extensibility occurs.

The results are shown in Table 6.

TABLE 6 Example Spun Draw Bi R i Pin Plate Filament Tensile Properties hl 5l Temp. Temp. Tenacity 2% Modulus Crystallfringcnce C C gm/denier Extension gm/den./ ine Regions l% Extn. /3-form 38 17x10 5.8 I05 196 8.8 7.7 194 39 5.8 I25 I96 9.2 7.5 200 8 40 5.8 150 196 8.9 6.3 l96 4l l25 l0" 3.2 I05 196 9.8 8.2 200 42 3.2 125 196 9.8 7.9 203 13 43 3.2 l50 I96 9.5 6.8 205 Examples 38, 39 and 40 are not according to the present invention.

EXAMPLES 44 52 Spun yarns were produced in a similar manner to that for Examples 38 43.

a. A 24 filament yarn of RV 2.08 was extruded at 312 C and collected at 3,500 fpm to give a spun yam which was amorphous and had a birefringence of 74 X b. A 24 filament yarn of RV 2.32 was extruded at 325 C and collected at 2,150 fpm to give a spun yarn which was partly a-crystalline and had a birefringence of 92 X 10*.

The two spun yarns were drawn at 350 fpm and a heated pin and plate to the appropriate maximum draw ratio using a fixed pin temperature while the plate temperature was varied. The effects of plate temperature on the tensile properties and on the percentage of B-crystalline form in the crystalline regions of the drawn yarns are shown in Table 7.

The results are shown in Table 7.

its copolyester in which at least 90 percent of the structural units are of the formula Q0 0-0 -emcm-owherein A is the spun yarn birefringence and W is the wind-up speed in feet per minute, and W has a range of 500 to 6,000, followed by orientation by hot drawing at a draw ratio substantially defined by the value of 4.0 at a birefringence of 74 X 10 3.5 at a birefringence of 92 X 10*, and 3.2 at a birefringence of 125 X 10 TABLE 7 Example Spun Yarn Extru- Draw Pin Plate Drawm Filament Tensile Properties Bire- RV sion Ratio C C [3- Tena- Exten- 2% l 00C fring- Temper- Form city sion Modulus Shrinkence ature gm/ gm/denJ age C denier l00% Extn 44 74X 2.08 3 l2 4.0 1 I5 175 2 8.5 6.0 l88 4.2

IO 45 4.0 120 I88 l2 l0.l 7.0 230 2.7 46 4.0 H5 198 22 9.9 7.3 222 2.5 47 4.0 120 205 I8 9.6 7.3 225 2.6 48 4.0 115 212 29 8.l 7.6 216 2.2 49 92X 2.32 325 3.5 125 176 4 8.4 6.4 173 4.0

.10- 50 3.5 I25 196 7 8.9 7.9 l 4.0 51 3.5 208 12 9.7 8.0 194 4.0 52 3.5 125 215 l3 9.0 8.2 177 3.8

At both levels of RV the proportion of Bform in- 65 at conventional temperatures.

creases with plate temperature whilst the tensile properties improve with increased plate temperature and 2. A process for the manufacture of a yarn according to claim 1 wherein the spun yarn birefringence is in excess of 1 10 X 10" but does not exceed the value given by the equation:

A= (16.2 X 10 W (50 X 10 is in the range from 295 to 335 C.

5. A process for the manufacture of a yarn according to claim 1 wherein cooling of the molten threadline is efi'ected by contact with the ambient air at normal 3. A process for the manufacture of a yarn according temperature and the relationship between spun yarn to claim 1 wherein said spun yarn is amorphous as judged by x-ray diffraction.

4. A process for the manufacture of a yarn according to claim wherein the relative viscosity of the poly- (ethylene-l :2-diphenoxyethane-4:4-dicarboxylate) or copolyester is up to 2.3 and the extrusion temperature relative viscosity and extrusion temperature is according to the following formula:

Extrusion temperature (89 X relative viscosity 

2. A process for the manufacture of a yarn according to claim 1 wherein the spun yarn birefringence is in excess of 110 X 10 3 but does not exceed the value given by the equation: Delta (16.2 X 10 6) W + (50 X 10 3).
 3. A process for the manufacture of a yarn according to claim 1 wherein said spun yarn is amorphous as judged by x-ray diffraction.
 4. A process for the manufacture of a yarn according to claim 10 wherein the relative viscosity of the poly-(ethylene-1:2-diphenoxyethane-4:4''-dicarboxylate) or copolyester is up to 2.3 and the extrusion temperature is in the range from 295* to 335* C.
 5. A process for the manufacture of a yarn according to claim 1 wherein cooling of the molten threadline is effected by contact with the ambient air at normal temperature and the relationship between spun yarn relative viscosity and extrusion temperature is according to the following formula: Extrusion temperature (89 X relative viscosity + 128)* C. 